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I agree, Al. Part of the value of this list is
exactly the different knowledge, experience and viewpoint of its members.
There are so many variables, its not hard to fixate on those which most support
a particular point of view(most often - our own viewpoint) {:>), until
alternative interpretations are presented for consideration.
I also agree that the "limits" on the rotary are probably
conservative - I mean I have hit 240F on the coolant (abeit for very short
periods) - did it shorten the life of the engine - don't know, hopefully not,
but nothing catastrophic happened, so I can live with it. But, on the
other hand, I don't have any more "authoritative" source on limits - so until
(as you point out) data to the contrary arrives, I will use the best I have as
guidelines.
I have overheated a rotary (caused me to lose the coolant
"O" ring seal), so I know it can happen - as others can attest to as well.
There is no question in my mind that the rotary is more heat sensitive than most
reciprocating engines - as Tracy pointed out - a lot more heat density in
parts of the block - which can quickly send temperatures rocketing upward - if
adequate cooling is not available. So others may have more design leeway
regarding the cooling system than the rotary.
Evan's works, but other than catastrophic boiling
protection, I fail to see any material benefit and the potential adverse effect
on the rotary would just make me very hesitant. If I had a cooling
problem, I would always look into the design or installation first. My
viewpoint is if water can not provide adequate cooling then my system needs a
redesign. But, again, that is just my personal opinion - and we all know
what opinions are worth {:>)
ED
----- Original Message -----
Sent: Sunday, January 07, 2007 9:01
AM
Subject: [FlyRotary] Re: Ideal
cooling
<<I do agree catastrophic boil-over is something
to be avoided. But, IF the problem is your system can't keep up with
your heat dissipation needs, then the system needs to be fixed,
substituting a coolant with less heat carrying capacity and raising
the operating temperature just does not seem the right course of action
- in my opinion.
>>
When I first looked into Evans years ago, saw the specific heat value,
then I too discounted it. I too thought it was a crutch for a bad cooling
design. At the time I reasoned that it would have to increase drag. And
it does...... if you assume all of the other factors are the same. However, if
the user just operated at a temperature 10 or 15F higher than normal, then
there is no drag increase. So as time has passed, I realized it can be a
significant safety advantage. Now I think it's worthy of consideration.
Tracy makes excellent point regarding nucleation.
That said, I too am resistant to using it. I never have, and prefer to do
everything I can to use conventional coolant and standard temperatures. But if
I'm unable to obtain the safety margin conventionally, then I will definitely
try it.
Racing Beat article is interesting. But I try to keep in mind that that's
just some guy writing the article. So I always seek other
evidence. If the author included facts that supported logic, then
I'd be much less skeptical. I am familiar with Asian design practices. They
put a great deal of effort into reducing sensitivity to things like coolant
and oil temp. They know that increasing that margin by 5 or 10F, they
dramatically reduce warranty issues and improve customer satisfaction. So if
the engine was temperature sensitive in the past, they would put lot's of
effort into reducing that.
Of course, I'm not encouraging running engine hotter. But I do encourage
skepticism.
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